Thus, an ongoing strategy of deterrence resulted in which it was perceived as necessary to maintain a large deployment of weapons in order to create the threat of retaliation for the enemy.

resulted在句中为不及物动词作谓语，in which到句末为主语的定语从句。为了避免头重脚轻，主语的定语从句移至谓语动词之后，构成所谓分隔式修饰（分隔式定语从句）。

which的先行词为句子的主语，in which在定语从句中作状语。it为从句的形式主语，真正主语为to maintain...for the enemy这个不定式短语。